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Synthesis, electrochemical and optical studies of poly(ethylene oxide) based gel-polymer electrolytes for sodium-ion secondary batteries
Solid State Ionics ( IF 3.2 ) Pub Date : 2021-09-21 , DOI: 10.1016/j.ssi.2021.115755
M. Menisha , S.L.N. Senavirathna , K. Vignarooban , N. Iqbal , H.M.J.C. Pitawala , A.M. Kannan

Sodium-ion batteries are being heavily investigated as cheaper alternatives to expensive lithium-ion batteries. However, synthesizing suitable electrolytes with sufficient ambient temperature ionic conductivities is a major bottleneck. In this work, gel-polymer electrolytes (GPEs) based on poly(ethylene oxide) (PEO) host polymer and NaClO4 ionic salt are developed by using ethylene carbonate (EC) and propylene carbonate (PC) plasticizer/solvent mixture. The optimized PEO:NaClO4:EC:PC composition (7:13:40:40 wt%) exhibits an ambient temperature ionic conductivity of 9.5 mS cm−1 and the variation of ionic conductivity with inverse temperature showed Arrhenius behavior with almost same activation energies for all the compositions. DC polarization studies on optimized composition reveals that the electrolyte is dominantly an ionic conductor (ti = 0.99) with negligible electronic conductivity (te = 0.01), which is highly desirable for an effective electrolyte. Cyclic voltammetric and linear sweep voltammetric studies confirm that the optimized composition is electrochemically stable for a voltage window of −1.85 to +1.85 V. Absence of any crystalline peaks in the X-ray diffractograms of the GPEs is a clear evidence for the amorphous nature of these GPEs. Broadening of the FTIR vibrational bands at 1000–1300 and 1700–1850 cm−1 is ascribed to the lowering of crystallinity resulting from the formation of PEO/Na+ complex through Na+ ion solvation by the polymer host. The GPE with optimized composition and highest ionic conductivity at ambient temperature is a suitable electrolyte for practical applications in sodium-ion batteries.



中文翻译:

用于钠离子二次电池的聚环氧乙烷基凝胶聚合物电解质的合成、电化学和光学研究

钠离子电池作为昂贵的锂离子电池的更便宜的替代品,正在被大量研究。然而,合成具有足够环境温度离子电导率的合适电解质是一个主要瓶颈。在这项工作中,通过使用碳酸亚乙酯 (EC) 和碳酸亚丙酯 (PC) 增塑剂/溶剂混合物开发了基于聚环氧乙烷 (PEO) 主体聚合物和 NaClO 4离子盐的凝胶聚合物电解质 (GPE) 。优化的 PEO:NaClO 4 :EC:PC 组合物 (7:13:40:40 wt%) 表现出 9.5 mS cm -1的环境温度离子电导率并且离子电导率随逆温度的变化显示出Arrhenius行为,所有组合物的活化能几乎相同。对优化组成的直流极化研究表明,电解质主要是一种离子导体(t i  = 0.99),其电子电导率可忽略不计(t e  = 0.01),这对于有效电解质来说是非常理想的。循环伏安法和线性扫描伏安法研究证实,优化的组合物在 -1.85 至 +1.85 V 的电压窗口内是电化学稳定的。 GPE 的 X 射线衍射图中没有任何结晶峰是无定形性质的明确证据这些 GPE。在 1000-1300 和 1700-1850 cm -1处拓宽 FTIR 振动带归因于聚合物主体通过 Na +离子溶剂化形成 PEO/Na +络合物导致结晶度降低。在环境温度下具有优化成分和最高离子电导率的 GPE 是钠离子电池实际应用的合适电解质。

更新日期:2021-09-21
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